slapt-src, spi: add page, slapt-get: fix example (#5014)

pages/linux/spi.md

@@ -0,0 +1,28 @@
+# spi
+
+> A meta package manager that handles both packages and slackbuilds.
+> More information: <https://github.com/gapan/spi>.
+
+- Update the list of available packages and slackbuilds:
+
+`spi --update`
+
+- Install a package or slackbuild:
+
+`spi --install {{package/slackbuild_name}}`
+
+- Upgrade all installed packages to the latest versions available:
+
+`spi --upgrade`
+
+- Locate packages or slackbuilds of interest by package name or description:
+
+`spi {{search_terms}}`
+
+- Display information about a package or slackbuild:
+
+`spi --show {{package/slackbuild_name}}`
+
+- Purge the local package and slackbuild caches:
+
+`spi --clean`